The alternator on your Cadillac DeVille powers the electrical system of your DeVille. Without the alternator, your Cadillac would not run, because the fuel system, braking system and even the steering system are all electronically controlled. Replacement alternators for your DeVille can be purchased from most auto parts stores. However, before replacing your alternator, you can use the built-in diagnostic system on your DeVille to determine if your alternator has failed.
Open the fuse panel cover underneath the steering wheel and locate the fuse for the alternator. Use the fuse diagram on the underside of the fuse panel cover to locate the fuse for the alternator.